Atomizing sprayer device

ABSTRACT

A hand held liquid sprayer for producing an atomizing mist includes an air and liquid control body attached to a spray head. The spray head contains an internal mixing chamber into which liquid and pressurized air are directed through respective liquid and air passages extending through the body and into the head. A circular spray tip in the mixing chamber directs the liquid radially outward into a perpendicular collision with high velocity air entering the chamber through a thin annular slot. The perpendicular impact of the expanding air breaks the liquid up into small particules which are then completely atomized by a further expansion as the mixture is sprayed through a nozzle. A staggered valve assembly operates in sequence to open the air passage before the liquid passage is opened and to close the liquid passage before the air passage is closed. A modification of the hand held liquid sprayer includes a second air passage to provide a separate blast of air prior to the beginning of the liquid spraying. The valve for the second air passage closes as the liquid valve is opened. A spray head for use in a fixed position includes a poppet valve which closes the liquid passage in the absence of air flow. The spray head is securable to a second identical spray head such that the same air and liquid inlet lines supply both spray heads and the two nozzles spray in opposite directions.

United States Patent 1191 OBrien Sept. 23, 1975 ATOMIZING SPRAYER DEVICE John W. O'Brien, 607 S. Kelly St., Harrison. Ark. 72601 [22] Filed: Aug. 7, 1974 [21] Appl. No.: 495,267

[76] Inventor:

Primary ExaminerRobert S. Ward, Jr. Attorney, Agent, or Firm-Lowe, Kokjer, Kircher [57] ABSTRACT A hand held liquid sprayer for producing an atomizing mist includes an air and liquid control body attached to a spray head. The spray head contains an internal mixing chamber into which liquid and pressurized air are directed through respective liquid and air passages extending through the body and into the head. A circular spray tip in the mixing chamber directs the liquid radially outward into a perpendicular collision with high velocity air entering the chamber through a thin annular slot. The perpendicular impact of the expanding air breaks the liquid up into small particules which are then completely atomized by a further expansion as the mixture is sprayed through a nozzle. A

staggered valve assembly operates in sequence to open the air passage before the liquid passage is opened and to close the liquid passage before the air passage is closed. A modification of the hand held liquid sprayer includes a second air passage to provide a separate blast of air prior to the beginning 0; he liquid spraying. The valve for the second air pas-m te closes as the liquid valve is opened. A spray head for use in a fixed position includes a poppet valve which closes the liquid passage in the absence of air flow. The spray head is securablc to a second identical; spray head such that the same air and liquid inlet lines supply both spray heads and the two nozzles spray in opposite directions.

8 Claims, 17 Drawing Figures [56] References Cited UNITED STATES PATENTS 1,070,872 8/1913 Bond 239/417.3 1,785,802 12/1930 Adams 239/434 1,876,643 9/1932 Downs 239/415 2,717,806 9/1955 Dale 239/415 2,753,578 7/1956 Lebet 239/289 X 2,930,533 3/1960 Maley et al.. 239/433 X 3,386,665 6/1968 10221 et a1. 239/4I6.4 X 3,421,693 1/1969 Fraser 234/434 x 3,493,181 2/1970 Goodnight et al. 239/434.5 X 3,515,353 6/1970 Young et a1. 239/434 X 3,658,255 4/1972 Beall 239/528 X FOREIGN PATENTS OR APPLICATIONS 502,786 2/1920 France 239/432 l /84 7o 66 as B r- 9- l 1 II US Patent Sept. 23,1975 Sheet 1 of3 3,907,207

US Patent Sept. 23,1975 Sheet 2 of 3 3,907,207

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ATOMIZING SPRAYER DEVICE BACKGROUND AND SUMMARY or THE INVENTION This invention relates generally to liquid sprayers for producing an extremely fine spray and finds particular utility in spraying release agents on dies and in other processes such as. but not limited to, heating fuel atomization, fuel carburetion, and general spray painting.

In spraying processes of the types mentioned, it is desirable to produce liquid droplets as small as possible in order to maximize the efficiency of the spraying operation. Since a smaller droplet has a greater area to volume ratio, it can contact the object surface more intimately and the surface can be properly covered by using a relatively small total quantity of liquid. It is therefore important that liquid sprayers be capable of spraying extremely fine liquid droplets;

As a rule, existing sprayers rely on air turbulence to produce small liquid particles. The air and liquid are mixed in the spray head and the turbulent action of the air. along with its expansion as it exhausts to the atmosphere through the nozzle, is used to break the liquid up into small droplets to be deposited onto the object. In order to produce the required degree of air turbulence, the air must be introduced under very high pressure, which leads to obvious safety problems. Since the conduits, seals, and valves must have a high structural strength in order to withstand the high pressure air, existing sprayers are costly to .manufacture, and those that are hand held are heavy and inconvenient to handle. Furthermore, if the air, is to be maintained in the proper turbulent condition, the pressure must be consistently held within a relatively'narrow range and pressure regulators are therefore required. As valves and seals become worn through age and use, the air pressure becomes difficult to maintainconstant and tends to fluctuate considerably, frequently resulting in a coarse, non-uniform spray.

The rate of liquid flow in most existing sprayers is set by a metering screw or similar member that requires tools for adjustment. The screw is initially set at a position wherein it is estimated that a desirable mixing ratio of air and liquid will be obtained. The effect of the spray is then observed, and since the initial estimate is invariably inaccurate. several trial and error tool adproper setting is achieved. In addition, existing sprayers typically lack a means for duplicating a desirable setting of the metering screw. A further problem is the tendency of unatomized liquid to exit from the nozzle of existing Sprayers as the air and liquid are shut off. Thus unatomized liquid is not only wasted, but it also clogs the nozzle orifices. This leads to a recurring maintenance problem which is compounded by the difficulty of dismantling existing Sprayers for cleaning and maintenance purposes.

As previously mentioned, the weight of existing hand held sprayers makes them difficult and cumbersome for the operator to handle. Sprayers are usually provided with a standard sized grip or handle which is fixed in position on the sprayer. Since the normal handle is not adjustable as to its position on the sprayer, each different operator cannot achieve a personally comfortable grip on the handle according to'his particular hand size. There is also the problem of temporarily storing the sprayer between uses. It is typically placed in a holding bracket or similar structure mounted to a wall which may be located some distance away from the area of use.

It is not uncommon for various types of debris to be located on the surface to be sprayed, either in the form of loose particles or material firmly adhered to the object surface. It is thus necessary to brush the loose particles from the object or to scrape the adhered material therefrom. Of course this increases the number of different implements required (i.e., brush, scraper, air blast, etc.) and further adds to the inconvenience.

When a pair of separate objects are to be sprayed, such as the opposite halves of dies used in die casting, it is the normal practice to utilize either a single spray head which is mounted in a fixed position to a bracket,

or a pair of separately mounted reciprocating spray of the time required to successively position and spray the two halves of the die, whereas the second practice requires the provision of a pair of additional inlet lines to supply air and liquid to the second spray head.

Consequently there is a need for a liquid sprayer which overcomes the aforementioned difficulties associated with existing sprayers. it is the primary goal of the present invention to meet that need.

More particularly, an object of this invention is to provide a sprayer that produces a uniform spray of finely atomized liquid particles. An important feature in this achievement is the provision of a novel spray head wherein the air is impacted at a right angle with the liquid to exert the maximum shearing force thereon. The resultant air-liquid mixture is caused to undergo additional expansion as it issues from the nozzle as in atomized mist.

Another object of the invention is to provide a sprayer of the character described that operates under low air and liquid pressure. Due to the novel spray head construction, the air need not be maintained in a turbulent state, and the air pressure requirement is therefore reduced considerably (for example to as low as approximately 30 psi), while the liquid pressure may be as low as atmospheric pressure in order to permit siphoning.

As a corollary to the preceding object, it is an aim of the invention to provide a sprayer of the character described in which air pressure fluctuations have little effect on the operation of the sprayer. It is a significant feature of theinvention that large fluctuations in the air and liquid pressure have little effect on the droplet size produced, while relatively large fluctuations in air pressure cause only insignificantly small fluctuations in the fluid flow rate.

Still another object of the invention is to provide a sprayer of the character described wherein the liquid 'flow rate may be adjustably metered without the need for tools.

Yet another object of the invention is to provide a sprayer of the character described in which unatomized liquid is prevented from leaking through the nozzle.

Another object of the invention is to provide, in a sprayer of the character described, an improved valve assembly for controlling the flow of air and liquid to the spray head without requiring special seals.

A further object of the invention is to provide a hand held sprayer that is easily and conveniently handled during operation. This feature is achieved by providing a sprayer that is light in weight and includes a smoothly sprayer head taken along line 55 3 contoured handle grip which is adjustable in position t the comfort of the operator.

A still further object of the invention is to provide a hand held sprayer of the character described that may be readily stored temporarily between uses. The provision of an adjustable hanger allows the-sprayer .to be hung on a pipe or other structure that is conveniently located in the spraying area. 3

Yet another object of the invention isto provide a hand held sprayer of the character described that is adapted to remove foreign material from the surface to be sprayed. The inclusion of a sharp edged scraper on the spray head permits convenient scraping of packed materialfrom the object surface, while the second embodiment of the hand held sprayer includes a separate air blast to blow loose material from the object surface- Still another object of the invention is to provide a novel spray head for use in fixed position. The provision of a unique poppet valve assures proper operation of the block type spray head and prevent unatomized liquid from clogging the noule.

As a corollary to the preceding object, it is among the goals ofv the invention to provide a spray head of the character described that is suitable for attachment to a second spray head such that the two interconnected heads spray in opposite directions. It is an important feature, of the invention that the two interconnected spray heads may be supplied with air and liquid from common air and liquid inlet lines, thereby eliminating the necessity of furnishing additional supply lines for the second spray head. I

Other'and'further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.

DETAILED DESCRIPTION OF THE INVENTION In the accompanying drawings which form a part of the specification and are .to be read in conjunction therewith and in which like reference numerals are utilized to indicate like parts in the various views:

FIG. I is a top plan view of a hand held sprayer constructed in accordance with a preferred embodiment of the invention. with a portion of the actuating lever broken away to show the air and liquid .valves lo'cated therebelow, and with the broken pipe portions indicating continuous length;

2 is a side elevational view of the device shown in FIG. 1;

' FIG. 3 is an enlarged. fragmentary sectional view taken along line 3-3 of FIG. 2 in the direction of the arrows; v

FIG. 4 s a sectional view taken along line 4-4of FIG. 3 in the direction of the arrows;

FIG. 5 is an enlarged sectional side view of the rection of the arrows; v

FIG; 6 is an enlarged plan view of the sprayer head taken along line 6-6 of FIG. 2 in the direction of the arrows;

FIG. 7, is a fragmentary sectional view of the liquid metering member threaded into vtheside of housing as shown in FIG. 3;

FIG. 8 is an enlarged sectional view taken through the valve housing with the valves shown in juxtaposition and the actuating lever at a position wherein the air valve is partially depressed not yet opened;

of FIG. I in the di-.

the value Fig. 9 is a fragmentary sectional view aken through the valve housing (similar to FIG. 3 )showing a second embodiment of the hand held sprayer wherein two air valves and one liquid valve are employed;

. a position wherein the air blast valve '5 substantially depressed. the air valve is partially depressed, and the liquid valve has not yet opened;

' FIG. 13 is a sectional side view of the sprayer head of the second embodiment;

FIG. 14 is an enlarged sectional view taken along line l4l4 of FIG. 13 in the direction of the arrows;

FIG. 15 is a sectional view of a spray head for use in a fixed position;

FIG. 16 is a sectional view taken along line I6I6 of FIG. 15; and

and the liquid valve has FIG. 17 is a side elevational view illustrating two of the spray heads shown in FIGS. 15 and 16 connected in a stacked relationship.

. Referring now to the drawings in detail, FIGS. I a a through 8 illustrate a first'preferred embodiment of the hand held spraying device 10. An air inlet pipe 1 l and a liquid inlet pipt '12 are connected to flexible hoses (not shown) of conventional air and liquid sources. 'lhe' forward ends of pipes 11 and 12 have external threads for mating connection with a pair of internally threaded openings I3 and 14 respectively, extending into the rear of a value housing 15. Slidably mounted on pipes 11 and 12 is a contoured handle grip 16 which includes two apertures through which pipes II and I2 extend. The grip 16 provides a smoothly contoured support for engagement preferably with the heel or lower palm of the the operators hand for comfort and convenience.

A-set screw within the handle 16 engages the pipes to fix the handle in a selected position according to comfort of fit and the size of the operator's hand.

As best shown in FIG. 3, valve housing 15 is provided with an internal air passageway 17 extending from the inner end of the opening 13- to the lower portion of a cylindrical opening 18 which extends into thevalve housing I5 from the top surface thereof. In a like manner, a liquid passageway 19 extends from opening 14 to a second cylindrical opening 20 which extends into the valve housing 15 from the top surface thereof at a rearward and sideward location with respect to opening 18.

Threaded into the openings I8 and 20 an air valve body or gland 22 and a liquid valve gland 23, respec-' tively. The valve glands 22 and 23 have respective hexagonal flanged heads 22a and 23a which matingly engage the top surface of valve housing [5. At their top and portions, valve glands 22 and 23 are of a q diameter substantially equal to the diameter of the respective cylindrical openings 18 and 20 in which they are contained so that a tight fit is achieved. while'each valve gland is recessed inwardly at an intermediate portion to a diameter less than that of its containing opening to present a generally annular space between the recessed portion of the gland and the opening. With particular reference to FIG. 8, the valve glands 22 and 23 are each provided with an upper O-ring 25a and 25b respectively. and a lower O-ring 26a and 26b. respectively, to effect a tight seal between the valve glands and the respective openings in which they are contained. The upper O-rings 25a and 2512 are fitted in annular recesses adjacently below the'flanged head of each valve gland, while the lower O-rings 26a and 26b are fitted in similar annular recesses formed near the bottom of each valve gland. It should be noted that the depth of the openings 18 and 20 is greater than the height of the inserted valve glands so that a small air chamber 27 is formed beneath air valve'gland 22 and a liquid chamber 28 is formed beneath liquid valve gland 23.

Air valve gland 22 has a central bore 30 therein which diverges outwardly in conical fashion at its extreme lower portion. A valve element comprising an air valve spool 31 is slidably received in bore 30.-Air valve spool 31 includes a head portion 31a, a stem portion 31b of reduced diameter, and a tapered portion 316-. It is to be noted that head portion 31a terminates in a square shoulder 31d. Spaced below tapered portion .31:- is a collar 31a of a diameter slightly larger than that of bore 30. Carried intermediately within a grooved recess on head portion 310 is a tightly fitting O-ring 3211, while another O-ring 33a is carried in the similar groove formed between tapered portion 31a and collar 3le. A spring 34:! is biased against the underside of collar 31a and seats within a recess 350 located at the bottom of cylindrical opening 18. The spring 34:: continually biases air valve spool 31 to its uppermost position whereby the central bore 30 is effectively sealed from air chamber 27 by O-ring 33a seating against the flared lower edge of the gland 22.

In a similar manner, a liquid valve spool 36 is slidably mounted in a bore 37 extending centrally through liquid valve gland 23 and includes a head portion 360, a stern 36b of reduced diameter, a tapered portion 366, and a collar 36e. Liquid valve spool 36 differs from air valve spool 31 only in that its head portion 36:! has a tapered shoulder 36d in contrast to the square shoulder 31d. Carried intermittently within a grooved recess on head portion 360 is a tightly fitting O-ring 32b, while the groove between tapered portion 360 and collar 36 carries another O-ring 33b. A spring 3412 is biased against the underside of tapered portion 36(- seats within a recess 36b located at the bottom of cylindrical opening 20. The spring 34b continually biases liquid valve spool 36 to its uppermost position whereby the central bore 37 is effectively sealed from liquid chamber 28 by O-ring 33b seating against the flared lower edge of the gland 23 in the position as shown in FIG. 8.

A plurality of small apertures 40 extend laterally through the recessed intermediate portion of air valve gland 22, providing communication between the portion of bore 30 surrounding the air valve stem 31b and an air exit passage 41 which extends generally for- -wardly within valve housing 15. Similarly, liquid valve gland 23 is provided with a plurality of apertures 42 through its recessed intermediate portion. Apertures 42 connect bore 37 with a liquid passage 43 which extends forwardly within valve housing 15. As FIGS. 3, 4 and 7 most clearly show. liquid passage 43 has a 90 turn therein and terminates at the inward portion of a cylindrical metering hole 47 which extends into one side of valve housing 15. A liquid exit passage 48 extends inwardly from metering hole 47 and turns 90 to extend forwardly within the valve housing.

With reference now particularly to FIG. 7, the cylindrical hole 47-is threaded in order to receive a metering member 50, the knob portion 50a of which protrudes from hole 47. The inward portion of member 50 is grooved to carry an O-ring 51 which provides a tight seal against the walls of metering hole 47. A needle valve 52 is threaded into a bore 53 located centrally within metering member 50 and protrudes beyond the inward end of member 50. The threaded relationship between needle valve 52 and member 50 permits adjustment of the valve position with respect to the metering member. The tip of needle valve 52 may be extended wholly or partially into liquid exit passage 48 as metering member 50 is threaded inwardly by rotation of its protruding knob portion 50a.

The surface of the valve housing surrounding the knob 50a may be provided with calibration marks (not shown) to assist in duplicating a desired setting of the metering member 50. For alignment with the calibration marks, a pointer 54 is carried in a transverse opening in knob 50a and protrudes sidewardly therefrom. A boss 55 (FIG. 2) projecting from the surface of the valve housing serves to limit the outward position of needle valve 52 by engagement with pointer 54 as the limiting position is reached. Boss 55 and pointer 54 thereby provide a maximum rate of fluid flow from passage 43 into passage 48.

To manipulate the valves, a plate-like hand lever 58 of a size slightly greater than the valve housing is pivotally mounted to a projection 59 extending upwardly from the top forward portion of valve housing 15. A pivot shaft 60 extends through projection 59 and through a pair of spaced forks 58a and 58b of the lever between which is received the projection 59. Upward pivoting of lever 58 is limited by engagement between its front surface 580 and the upper edge 59a of projection 59, while lever 58 may be pivoted downwardly to contact and depress the twovalve spools 31 and 36.

As shown in FIG. 3, a sleeve 62 is threaded into a cylindrical opening 63 which is recessed into the front surface ofvalve housing 15; The respective air and liquid passages 41 and 48 terminate at opening 63. Sleeve 62 contains the rearward end of an elongate pipe 64, the hollow interior of which thereby communicates with the air exit passage 41. A small diameter conduit or tube extends centrally within elongate pipe 64 throughout the length thereof, and the rearward end of tube 65 extends tightly into liquid exit passage 48. The pipe 64 and tube 65 extend from the valve housing 15 to the spray head to be described.

FIGS. 1 and 2 illustrate a slidable hanger 66 having a hook-like tip 660. Hanger. 66 is slidably mounted on pipe 64 by means of a bore through its body portion, and the hanger may be fixed in a desired position on pipe 64 by a set screw 66]). 7

Threaded onto the forward end of pipe 64 is a sprayer head 70. Referring now to FIG. 5 which shows the interior of sprayer head 70 in cross section, the forward end of tube 65 fits tightly into an -L-shaped liquid passageway 71, and the hollow interior of pipe 64 communicates with a short angled air passageway 72. Liquid passageway 71 passes centrally through a cylindrical boss 73 and terminates at an annular mixing chamber 74. A cylindrical spray tip formed as part of a nozzle is disposed centrally in mixing chamber 74 with its circular inward surface 75:: spaced immediately ahead of and perpendicular to liquid passageway 71.

An annular chamber 76 surrounds boss 73 and communicates with the end of air passageway 72. A washer 77 having a bore slightly larger than boss 73 surrounds the end of the boss to substantially separate annular chamber 76 from mixing chamber 74, the two chambers being connected only by a small annular slot 78 formed as a result of the clearance between boss 73 and washer Nozzle 80 has a plurality of orifices 81 therein which provide access from mixing chamber 74 to the outside atmosphere. A retaining nut 82 having a central bore is threaded into an opening in the face of sprayer head 70..The body of nozzle 80 extends through the bore in nut 82, while the nut engages an enlargedflange 80a formed on the inward end of nozzle 80-to retain the nozzle and the washer 77 located therebehind in position within head 70. Finally, a scraper 83 having a sharp edge 83a suitable for scraping purposes is secured to the top of sprayer head 70 by a pair of screws In operation, respective sourcesof pressurized air and pressurized or atmospheric liquid are connected to air and liquid inlet pipes 1 1 and 12, and handle 16 is secured in a convenient position near valve housing 15. Knob 50a is rotated to an appropriate position wherein needle valve 52 permits the desired liquid flow rate. The threads of metering member 50 and the tight fit of O-ring 51 in hole 47 firmly hold member 50 in its set position, while the setting may be varied if desired by rotating knob 5011. As hand lever 58 is pivoted downwardly to overcome the upward biasing force of springs 34a and 34b and depress valve spools 31 and 36, the staggered locations of the valves causes air valve spool 31 to be contacted and depressed by the lever before liquid valve spool 36 is engaged thereby. At this point, the valves are in the position illustrated in FIG. 8, with air valve spool 31 slightly depressed and lever 58 just moving into engagement with liquid valve spool 36. The depression of air valve spool 31 has caused its lower O-ring 33a to move downwardly against the force of spring 34a from its sealing position in abutment with the flared lower edge of air valve gland 22. Consequently, the air that'has been introduced into air chamber 27 through pipe 11 and passage 71 is permitted to flow from the air chamber upwardly into bore 30, exiting from the bore into air exit passage 41 through apertures 40 and the annular space surrounding the -recessed intermediate portion of valve gland 22. The precedes then passes to sprayer head 70 through elongate pipe 64 and exhausts to the atmosphere through nozzle 80 in a high velocity jet produced by passage through the restricted slot 78. It is noted that at this point the bottom O-ring 33b of liquid valve spool 36 is seated in abutment with the flared lower edge of liquid valve gland 23 providing an effective seal between liquid chamber 28 and bore 37 so that liquid is prevented from flowing to the sprayer head. Thus as the sprayer is operated, a blast of air alone from the nozzle preceds the beginning of the liquid spraying.

needle valve 52 at a predetermined rate set by the position of metering member 50. The liquid then continues into liquid exit passage 48 and through the small tube 65 to the sprayer head. It is to be noted that simultaneously with the opening of the liquid valve by the additional downward pivoting of lever 58, the square shoulder portion 31d of air valve spool 31 is pushed downwardly the position shown by broken line of FIG. 8, and thus restricts somewhat the air flow from bore 30 to the apertures 40, providing only the amount of air necessary for spraying purposes. Since it is desirable for a relatively high flow rate of air for the air blast alone, shoulder 31d does not interfere with the flow of air into apertures 40 unless the liquid valve is in the open position. 7

When the spraying begins as both valve spools 31 and 36 are depressed, the interaction between the air and liquid thereby .entering sprayer head is best understood with reference, to FIG. 5. The liquid from the small tube 65 enters liquid passageway, from where it perpendicularly impinges on the circular flat surface 751:. This perpendicular collision with the spray tip reflects the liquid radially outwardly from surface a in a thin sheet. Simultaneously, the air flowing from air passageway 72 into the annular chamber 76 is forced through the reduced area clearance slot 78, the restriction in area producing a corresponding increase in the velocity of the air. As the high velocity air enters mixing chamber 74 from slot 78, a first expansion occurs since the pressure .in the mixing chamber is considerably less than that in the annular chamber 76. The high speed, expanding air from slot 78 is directly circumferentially past circular surface 75a at a right angle with respect to the surface 75a, thereby colliding at a right angle with the thin sheet of liquid radiating outwardly from surface 75a. The shearing force exerted on the liquid is maximum because of the right angle collision, and this'powerful shearing force. along with the expansion of air, divides the liquid into extremely small particles containing a quantity of air. As these small particles exhaust to the atmosphere through nozzle 80 a further expansion due-to the relatively low, atmospheric pressure completes the atomization process and breaks theliquid particles up into even smaller particles which spray from the nozzle in a finely atomized mist. The right angle collision between the air and liquid occurs at the point of lowest pressure in the air stream, allowing liquid-to be siphoned if desired.

When lever 58 is released to discontinue spraying, the actionof springs 34a and 34b force the respective air and liquid valve spools 31 and 36 upwardly to their sealing positions wherein bores 30 and 37 are again sealed against flow. Due to the location of liquid valve spool 36 farther from the pivot axis of lever 58 than air valve spool 31, O-ring 33b moves into abutment with the flared lower edge of liquid valve gland 23 to cut off the liquid flow before the O-ring 330 on the air valve spool moves upwardly to its sealing position against the flared lower edge of air valve gland 22 to cut off the air flow. The liquid flow is thus always cut off prior to the air flow, and any liquid remaining in sprayer head 70 after the liquid flow is stopped is acted on by a short blast of air before the air flow stops. In this manner. unatomized liquid is precluded from dripping through nozzle 80'and clogging the orifices thereof.

Referring now to 'FlGS.'9 through 14, a second embodiment of the hand held spraying device is generally designated by numeral 10. The sprayer 10 is similar in construction to the first embodiment, with the main modification being that sprayer 10' includes a second air path to produce a separate blast of air and an additional valve to regulate the airflow therethrough. Like part in the first and second embodiments are designated by the same numerals with primes added thereto in FIGS. 9-14, and the primed numerals indicate parts corresponding to those previously described in the first embodiment, except for certain changes that are hereinafter set forth. 7

With initial reference to FIGS. 9 and 10, the rearward top portion of valve housing (which may be enlarged to accommodate the added valve) includes'a boss 151: located rearwardly on the valve housing relative to openings 18' and 20'. A threaded opening 21 extends downwardly into boss 15a with its bottom portion connected to an intermediate portion of the air passageway 17. It is noted that air passageway 17' provides an air inlet to both openings 18 and 21'. An air blast valve gland 24' with a bore 38 having an enlarged lower portion is threaded into opening 21'. Valve gland 24 includes a hexagonal flanged head 24a and has top and bottom portions substantially equal in diameter to opening 21', while an intermediate portion of valve gland 24 is recessed to a lesser diameter than that of opening 21. For sealing purposes, an upper O-ring 25c is fitted in a groove in the upper portion of valve gland 24', and a lower O-ring 260 is fitted in a similar groove in the lower portion of valve gland 24. Since valve gland 24' is shorter than the depth of opening 21, an air chamber 29 is formed beneath the gland.

Slidable within the central bore 38 in valve gland 24' is an air blast valve spool 39 having a head 39a, a stem 39b of reduced diameter, a tapered portion 390', and a collar 39e'. It is to be noted that in the second embodiment all three valve spools 31, 36 and 39' include a tapered shoulder 31d, 36d, and 39d, respectively, on the underside of their heads. It is further pointed out that air blast valve spool 39' is of slightly greater height than the other two spools 31 and 36 and carries a pair of O-rings 32c and 32d in respective grooves in its head, as well as the O-ring 336 between tapered portion 390 and collar 3%. Like the other two valve elements, air blast valve spool 39' has a spring 340' biased against the underside of its collar 39:2 and seating in a recess 35c located at the bottom of opening 21. Spring 34c continuously biases air blast valve spool 39 to its uppermost position whereby bore 38' is sealed from air chamber 29 by O-ring 33c seating against the flared lower edge of gland 24. The recessed intermediate portion of air blast valve gland 24 includes a plurality of apertures 44 connecting bore 38 with the generally annular space surrounding the recessed gland portion and an air blast exit passage 45. As in the first embodiment, liquid exit passage 48' connects to the hollow interior of the small elongate tube 65'. However. in the second embodiment, unlike the first embodiment. tube 65' is surrounded by a larger diameter tube 61. As FIGS. 9 and 10 illustrate, air exit passage 41' connects with the hollow interior of tube 61 while the forwardly extending air blast passage 45 connects with the interior of the elongate pipe 64 which is threaded into a cylindrical opening 63' in the front surface of valve housing 15 and which surrounds tubes 61 and 65'.

FIG. 13 shows the connection of pipe 64' and tubes 61' and 65 with the sprayer head Sprayer head 70 has the same internal structure as described for the head 70 of the first embodiment to direct air and liquid into a right angle collision within the sprayer head. However, sprayer head 70 includes an additional passageway 79 to provide a separate path for the air flowing through the large pipe 64. Liquid from the innermost tube 65 enters liquid passageway 71 from where it is directed into a collision with the air which enters air passageway 72' from tube 61 by means of the previously described internal structure of the sprayer head. Connected with the hollow interior of pipe 64' is the air blast passageway 79 which has a right angle turn therein. A second and smaller nozzle 84 which exhausts to the atmosphere is threaded into head 70 forwardly of nozzle 80. Nozzle 84' connects to air blast passageway 79 and includes a plurality of pressure relief holes 85' extending through the side thereof at an upward angle to prevent the pressure buildup from exceeding a safe level.

The operation of the second embodiment is similar to that of the first, except that a separate blast of air from nozzle 84 precedes the spraying in order to blow loose particles from the surface of the object to be sprayed. With particular reference to FIG. 11 it is apparent that due to its elevated position, air blast valve spool 39' is the first valve to be contacted and depressed by lever 58. The depression of valve spool 39 permits the air that enters chamber 29 from passage 17 to pass into bore 38', and from there through apertures 44', pas sage 45, and pipe 64 to sprayer head 70 for exhaust through nozzle 84. As lever 58' is pivoted further downwardly, air valve spool 31' is next depressed because of its position nearer the pivot axis than the liquid valve spool 36.

The position shown by FIG. 12 is one wherein air blast valve spool 39 is depressed almost totally, air valve spool 31' is depressed only partially, and liquid valve spool 36' has not yet been depressed. It is to be noted that additional downward pivoting of lever 58' from the FIG. 12 position not only opens liquid valve spool 36 to permit the flow of liquid, but also depresses the O-ring 32c carried on the head portion of air blast valve spool 39' to a position below apertures 44'. This action of O-ring 32c effectively seals apertures 44 from chamber 29 and thereby cuts off the air blast from nozzle 84'. The elevated position of air blast spool 39 causes lever 58' to depress it to a greater depth within its bore as compared to maximum depression of the other two valv'e spools. The additional downward travel of air blast valve spool 39' as lever 58' is pivoted into contact with liquid valve spool 36' results in the separate air blast from nozzle 84' being cut off by O-ring 320 as the spraying of liquid from nozzle 80' begins.

The spraying of the air-liquid mixture from nozzle 80 begins as previously related when lever 58 is pivoted downwardly past the FIG. 12 position to open liquid valve 36. In the manner described in connection with the first embodiment, a finely atomized mist sprays from nozzle 80' as a result of the right angle collision of the air and liquid in conjunction with the double expansion produced by sprayer head 70.

Turning now to FIGS. 15 through 17, an embodiment of a spray head for use in a fixed position is generally designated by the numeral 10". Although this embodiment produces a right angle collision between the air and liquid in a similar manner as the other twoembodiments, the entirety of sprayer comprises a block type sprayer head 70" which is mounted in a fixed position to a wall or ceiling or to a bracket which is positionally adjustable. The spray head 70 is so constructed as to be stackable upon a second identical head such that the respective nozzles point in opposite directions, an arrangement suitable for simultaneously spraying opposite halves of a die or other object having two separate, opposing parts.

The top surface of head 70" has a pair of cylindrical threaded openings 88" and 89" extending therein which are adapted for connection to respective air and liquid supply lines 90" and 91". It is preferred that this connection be sufficiently rigid as to serve as the sole means for mounting the spray head. Accordingly, the openings 88" and 89" preferably receive respective quick disconnect couplings 88a" and 89a which rigidly connect hoses 90" and 91" to head 70". A threaded recess 92 is provided in a side of head 70 to serve as an additional mounting means.

Referring particularly to FIG. 15, opening 88" terminates at a small air passage 93", while opening 89" connects at its end with a liquid passage 94". Passages 93" and 94" extend downwardly in spaced relation to pass from spray head 70" through the bottom surface thereof. At their bottom portions, passages 93" and 94" are enlarged somewhat and are threaded to receive set screws (not shown).

A metering member 50" having a hexagonal flanged head 50a" is threaded into an opening 47" formed in the side of head 70 opposite the threaded recess 92". Metering member 50" has a needle valve 52" threaded in its central bore and projecting inwardly therefrom to extend transversely through a portion of liquid passage 94. Needle valve 52 also projects into another liquid passage 95" which connects at'a right angle with an intermediate portion of passage 94" and extends inwardly therefrom. The inward portion of metering member 50" is grooved to carry an O-ring 51" which provides a tight seal against the walls of opening 47". A vertical pin 96" (FIG. 16) located in a groove at the side of opening 47" engages the opposite ends of an annular groove 50b" formed intermediately on member 50" to limit the distance member 50" may travel with respect to opening 47". Metering member 50 preferably includes a pointer member or the like that extends from head 50a" and aligns with calibration marks (not shown) on the surrounding surface of the spray head to permit duplication of settings of member 50".

Intermediately along air passage 93", a passage 97 connects thereto at a right angle. Passage 97" in turn connects at one end to an annular chamber 76" and at its other end to a bifurcated bore 98" formed in the side of head 70". Bore 98" has an outer portion 98a of larger diameter than its inward portion 9812, which connects to the liquid passage 95" at its extreme end.

A poppet valve 99" having an enlarged head and a reduced diameter stem is slidably disposed in bore 98 with its head located in enlarged bore portion 98a and its stem in the smaller bore portion 98b". The head of poppet valve 99 comprises a pair of spaced flanges 99a" and 99b" ofa diameter substantially equal to that of bore portion 98a. A groove formed between flanges 99a and 991) carries an O-ring 100 which provides a seal against the walls of bore portion 98a".

The stem of poppet valve 99" extends centrally from the flat surface of flange 99b" and carries an O-ring 101 in a groove formed between its top portion 99c" and an intermediate collar 99d". Portion 99c" and collar 99d have diameters equal to the bore portion 981)", while collar 99d" is tapered downwardly. The stem terminates in a frusto-conical tip 9% and carries a small O-ring 102" in a groove formed between tip 99e" and collar 99d". The inward movement of poppet valve 99" is limited by engagement of flange 99b" with the shoulder formed between the bore portions 98a" and 9812.

A spring 103 is utilized to continually bias poppet valve 99 inwardly toward a position wherein the small O-ring 102 is seated on a flared shoulder 71a" which forms the entrance to a liquid passageway 71 having an enlarged inward portion which tapers to a smaller outward portion. One end of spring 103" is fitted in a short central recess 104 in the outward face of the poppet valve head while the opposite end of the spring seats in a recess 105" formed centrally in a retaining member 106". The retainer 106" is secured by a snap ring 106:! or the like received in a groove formed in the side walls of bore 98 in order to retain poppet valve 99" in the bore. It is noted that there is a clearance between valve 99" and retainer 106" so that the valve may be moved outwardly a short distance in response to pressure upon the inward surface of flange 99!).

Liquid passageway 71 extends centrally through a cylindrical boss 73" which is turn extends centrally through the annular chamber 76". A washer 77" having a bore slightly larger than boss 73 is positioned around the end of boss 73" to present a small annular slot 78 between the boss and washer. Washer 77" is retained in position by a nozzle 80" which is threaded into an opening in the face of head opposite bore 98". The inward portion of nozzle 80" includes a cylindrical spray tip having a flat, circular inward surface 75a". Surface 75:!" is spaced immediately ahead of the end of liquid passageway 71" and is oriented perpendicular thereto. An annular mixing chamber 74" formed around spray tip 75" communicates with chamber 76 through the small slot 78". A plurality of orifices 81" extend through nozzle from mixing chamber 74 to exhaust to the atmosphere.

Opposite comers of spray head 70" are bored with bolt holes 108a" which extend entirely through the head from top to bottom, while a second pair of bolt holes 108b" which are threaded extend only partially into the head from the bottom thereof at the other two corners. By inserting appropriate bolts into the bolt holes of a pair of identical spray heads 70", the two heads may be stacked together in an inverted relationship with the respective nozzles 80" spraying in opposite directions as shown in FIG. 17. Since air and liquid passages 93" and 94" extend entirely through the spray head, the two heads are stacked with their re spective air passages 93" interconnected and their respective liquid passages 94" interconnected. A pair of O-ring seals 109a and 1091;" (FIG. 15) which seat in grooves formed around the respective passages 93" and 94" at the extreme ends thereof are utilized to effect a seal between the connected passages when the two heads are bolted together. The threaded air and liquid inlet openings 88" and 89" of the bottom head may be sealed by pipe plugs 110 in combination with a sealing compound. In this manner a single air source and a single liquid source supply both of the stacked heads. Of course. if it is desired to utilize only a single spray head 70" the lower ends of air passage 93"'and liquid passage 94" may be sealed by set screws and sealing compound (not shown) or by other suitable means.

To operate the sprayer head 70", the metering member 50" is set to permit a desirable rate of liquid flow. and the respective air and liquid sources are turned on. As the air thereby entering air passageway 97" from passage 93" exerts rearward pressure upon the surface of flange 98b", O-ring 102" is unseated from shoulder 71a", and liquid is permitted to flow from passage 94" into passage 95". through the end of bore portion 98b", and into liquid passageway 71. From passage 71" the liquid perpendicularly impinges on the circular flat surface 75a" and is reflected radially outwardly therefrom in a thin sheet. Simultaneously the air flowing from passage 97 into annular chamber 76 is forced through the small annular slot 78" and circumferentially past circular surface 75a" in a direction perpendicular thereto. Passage through the restricted area slot 78" produces an increase in the velocity of the air. which also expands as it enters mixing chamber 74" because of the decreased pressure therein relative to chamber 76". The high speed, expanding air directed past surface 75:!" is caused to collide at a right angle with the thin sheet of liquid radiating outwardly from surface 75a", thereby exerting the maximum shearing force on the liquid. The powerful shearing force, along with the expansion of the air, divides the liquid into extremely small particles containing a quantity of'air. As these small particles exhaust to the atmosphere through nozzle 80", a further expansion due to the relatively low atmospheric pressure completes the atomization process and breaks the liquid up into even smaller particles which spray from nozzle 80 in a finely atomized mist.

It is noted that unless the air source is on, the biasing force of spring 103" on poppet valve 99" seats O-ring 102" on shoulder 71:!" to seal off the flow of liquid. However, when air pressure is exerted on flange 99b", poppet valve 99 is forced outwardly to unseat O-ring 102" from shoulder 71a" and permit liquid to flow through spray head 70. [n this manner, the action of poppet valve 99" permits liquid flow only if there is also air flow and thereby prevents unatomized liquid from dripping through nozzle 80".

From the foregoing it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is comtemplated by and is within the scope of the claims.

Since many possible embodiments may be made of the invention without departing from the scope thereof. it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpretcd as illustrative and not in a limiting sense.

Having thus described my invention, 1 claim:

l. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising:

a spray head having an air-liquid mixing chamber therein;

liquid delivery means interconnecting said spray head and said liquid source;

air delivery means interconnecting said spray head and said air source;

a liquid passage disposed through said spray head for directing liquid from said liquid delivery means to said mixing chamber, said liquid passage including a central liquid discharge orifice to said mixing chamber; I

an air passage disposed through said spray head for discharging air from said air delivery means to said mixing chamber, said air passage including a circular discharge annulus to said mixing chamber concentrically disposed with respect to said liquid orifice to deliver an annular curtain of air substantially parallel to the liquid issuing from said liquid orifice to the mixing chamber;

a liquid impingement member disposed within said mixing chamber and having a flat circular impingement surface substantially perpendicular to said liquid orifice to cause liquid issuing therefrom to spread radially outward and perpendicularly intersect said annular curtain of air to form an intimate admixture of air and liquid; and

a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge said mixture of air and liquid in said chamber to the atmosphere as a fine liquid spray.

2. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising:

a spray head having an air-liquid mixing chamber therein;

liquid delivery means interconnecting said spray head and said liquid source;

air delivery means interconnecting said spray head and said air source;

a liquid passage disposed through said spray head for directing liquid from said'liquid delivery means to said mixing chamber;

an air passage disposed through said spray head for discharging air from said air delivery means to said mixing chamber;

a control valve disposed in said spray head communicating with said air and liquid passages, said valve yieldably biased to normally close said liquid passage and responsive to the pressure of the air supplied to said air passage to open said liquid passage;

a liquid impingement member disposed within said mixing chamber to direct liquid delivered through said liquid passage into a substantially perpendicular intersection with air discharged through said air passage to form an intimate admixture of air and liquid; and

a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge said admixture of air and liquid in said chamber to the atmosphere as a fine liquid spray.

3. The spraying apparatus as in claim 2 including an adjustable liquid flow regulator mounted on said spray head and associated with said liquid passage to adjustably meter liquid flow therethrough.

4. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising:

a first spray head having an air-liquid mixing chamber therein;

liquid delivery means interconnecting said first spray head and said liquid source;

air delivery means interconnecting said first spray head and said air source;

a liquid passage disposed through said first spray head for directing liquid from said liquid delivery means to said mixing chamber;

an air passage disposed through said first spray head for discharging air from said air delivery means to said mixing chamber;

a liquid impingement member disposed within said mixing chamber of said first spray head to direct liquid delivered through said liquid passage into a substantially perpendicular intersection with air discharged through said air passage to form an intimate admixture of air and liquid;

a discharge orifice disposed through said first spray head communicating said mixing chamber with the atmosphere to discharge said admixture of air and liquid in said chamber to the atmosphere as a fine liquid spray;

a second spray head having an air-liquid mixing chamber therein;

a liquid passage disposed through said second spray head for directing liquid to said mixing chamber; an air passage disposed through said second spray head for discharging air to said mixing chamber;

a liquid impingement member disposed within said mixing chamber of said second spray head to direct liquid delivered through said liquid passage into a substantially perpendicular intersection with air discharged through said air passage to form an intimate admixture of air and liquid;

a discharge orifice disposed through said second spray head communicating said mixing chamber with the atmosphere to discharge said admixture of air and liquid in said chamber to the atmosphere as a fine liquid spray;

air coupling means interconnecting said air passage of said first spray head with said air passage of said second spray head whereby air supplied by said air delivery means serially flows through said first spray head to said second spray head; and

liquid coupling means interconnecting said liquid passage of said first spray head with said liquid passage of said second spray head whereby liquid supplied by said liquid delivery means serially flows through said first spray head to said second spray head.

5. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising;

a valve body;

liquid delivery means interconnecting said valve body and said liquid source;

air delivery means interconnecting said valve body and said air source;

a spray head connected to said valve body and having an air-liquid mixing chamber therein;

a liquid passage disposed through said valve body and through said spray head for delivering liquid from said liquid delivery means to said mixing chamber;

an air passage disposed through said valve body and through said spray head for discharging air from said air delivery means to said mixing chamber;

a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge air and liquid within the chamber to the atmosphere;

an air valve mounted on said valve body and associated with said air passage, said air valve being selectively open and closed to respectively permit and prevent air flow through said air passage;

a liquid valve mounted on said valve body and associated with said liquid passage, said liquid valve being selectively open and closed to respectively permit and prevent liquid flow through said liquid passage;

valve activating means mounted on said valve body to open and close said air and liquid valves in such a manner that said liquid valve may be opened only if said air valve is first opened and said air valve is closed only if said liquid valve is first closed;

an adjustable liquid flow regulator mounted on said valve body and associated with said liquid passage to adjustably meter liquid flow therethrough;

a stop member disposed on said valve body to engage said liquid .flow regulator and limit the maximum liquid flow through said liquid passage; and

calibration means associated with said valve body adjacent said liquid flow regulator to indicate the position of said regulator and the liquid flow through said liquid passage.

6. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising:

a valve body;

liquid delivery means interconnecting said valve body and said liquid source;

air delivery means interconnecting said valve body and said air source;

a spray head connected to said valve body and having an air-liquid mixing chamber therein;

a liquid passage disposed through said valve body and through said spray head for delivering liquid from said liquid delivery means to said mixing chamber;

an air passage disposed through said valve body and through said spray head for discharging air from said air delivery means to said mixing chamber;

a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge air and liquid within said camber to the atmosphere;

an air valve mounted on said valve body and having an air spool piece disposed within said air passage and yieldably biased to a closed position in order to block air flow through said air passage, and partially depressible in order to permit unrestricted air flow through said air passage, said spool piece including air flow restriction means to limit air flow through said air passage when said spool piece is fully depressed;

a liquid valve mounted on said valve body and associated with said liquid passage, said liquid valve being selectively open and closed to respectively permit and prevent liquid flow through said liquid passage; and valve activating means mounted on said valve body to open and close said air and liquid valves in such a manner that said liquid valve may be opened only if said air valve is first opened and said air valve is closed only if said liquid valve is first closed. 7. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising:

a valve body;

a liquid delivery means interconnecting said valve body and said liquid source;

air delivery means interconnecting said valve body and said air source;

a spray head connected to said valve body and having an air-liquid mixing chamber therein;

a liquid passage disposed through said valve body and through said spray head for delivering liquid from said liquid delivery means to said mixing chamber;

a first air passage disposed through said valve body and through said spray head for discharging air from said air delivery means to said mixing chamber;

a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge air and liquid within said chamber to the atmosphere;

a first air valve mounted on said valve body and associated with said first air passage, said air valve being selectively open and closed to respectively permit and prevent air fiow through said first air passage;

a liquid valve mounted on said valve body and associated with said liquid passage, said liquid valve being selectively open and closed to respectively permit and prevent liquid flow through said liquid passage;

an air blast orifice associated with said spray head;

a second air passage disposed through said spray head and through said valve body and communicating with said air blast orifice to discharge air therefrom supplied by said air delivery means;

a second air valve mounted on said valve body and associated with said second air passage, said second air valve being selectively open and closed to respectively permit and prevent air flow through said second air passage; and

valve activating means mounted on said valve body to open and close said air valves and said liquid valve in such a manner that said liquid valve may be opened only if said air valve is first opened, said first air valve is closed only if said liquid valve if first closed, said second air valve may be opened only if said liquid valve is closed, and said second air valve is automatically closed when said liquid valve is opened.

8. The spraying apparatus as in claim 7 including at least one pressure relief hole extending from said second air passage to the atmosphere to prevent air pressure in said second air passage from exceeding a predetermined level. 

1. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising: a spray head having an air-liquid mixing chamber therein; liquid delivery means interconnecting said spray head and said liquid source; air delivery means interconnecting said spray head and said air source; a liquid passage disposed through said spray head for directing liquid from said liquid delivery means to said mixing chamber, said liquid passage including a central liquid discharge orifice to said mixing chamber; an air passage disposed through said spray head for discharging air from said air delivery means to said mixing chamber, said air passage including a circular discharge annulus to said mixing chamber concentrically disposed with respect to said liquid orifice to deliver an annular curtain of air substantially parallel to the liquid issuing from said liquid orifice to the mixing chamber; a liquid impingement member disposed within said mixing chamber and having a flat circular impingement surface substantially perpendicular to said liquid orifice to cause liquid issuing therefrom to spread radially outward and perpendicularly intersect said annular curtain of air to form an intimate admixture of air and liquid; and a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge said mixture of air and liquid in said chamber to the atmosphere as a fine liquid spray.
 2. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising: a spray head having an air-liquid mixing chamber therein; liquid delivery means interconnecting said spray head and said liquid source; air delivery means interconnecting said spray head and said air source; a liquid passage disposed through said spray head for directing liquid from said liquid delivery means to said mixing chamber; an air passage disposed through said spray head for discharging air from said air delivery means to said mixing chamber; a control valve disposed in said spray head communicating with said air and liquid passages, said valve yieldably biased to normally close said liquid passage and responsive to the pressure of the air supplied to said air passage to open said liquid passage; a liquid impingement member disposed within said mixing chamber to direct liquid delivered through said liquid passage into a substantially perpendicular intersection with air discharged through said air passage to form an intimate admixture of air and liquid; and a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge said admixture of air and liquid in said chamber to the atmosphere as a fine liquid spray.
 3. The spraying apparatus as in claim 2 including an adjustable liquid flow regulator mounted on said spray head and associated with said liquid passage to adjustably meter liquid flow therethrough.
 4. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising: a first spray head having an air-liquid mixing chamber therein; liquid delivery means interconnecting said first spray head and said liquid source; air delivery means interconnecting said first spray head and said air source; a liquid passage disposed through said first spray head for directing liquid from said liquid delivery means to said mixing chamber; an air passage disposed through said first spray head for discharging air from said air delivery means to said mixing chamber; a liquid impingement member disposed within said mixing chamber of said first spray head to direct liquid delivered through said liquid passage into a substantially perpendicular intersection with air discharged through said air passage to form an intimate admixture of air and liquid; a discharge orifice disposed through said first spray head communicating said mixing chamber with the atmosphere to discharge said admixture of air and liquid in said chamber to the atmosphere as a fine liquid spray; a second spray head having an air-liquid mixing chamber therein; a liquid passage disposed through said second spray head for directing liquid to said mixing chamber; an air passage disposed through said second spray head for discharging air to said mixing chamber; a liquid impingement member disposed within said mixing chamber of said second spray head to direct liquid delivered through said liquid passage into a substantially perpendicular intersection with air discharged through said air passage to form an intimate admixture of air and liquid; a discharge orifice disposed through said second spray head communicating said mixing chamber with the atmosphere to discharge said admixture of air and liquid in said chamber to the atmosphere as a fine liquid spray; air coupling means interconnecting said air passage of said first spray head with said air passage of said second spray head whereby air supplied by said air delivery means serially flows through said first spray head to said second spray head; and liquid coupling means interconnecting said liquid passage of said first spray head with said liquid passage of said second spray head whereby liquid supplied by said liquid delivery means serially flows through said first spray head to said second spray head.
 5. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising; a valve body; liquid delivery means interconnecting said valve body and said liquid source; air delivery means interconnecting said valve body and said air source; a spray head connected to said valve body and having an air-liquid mixing chamber therein; a liquid passage disposed through said valve body and through said spray head for delivering liquid from said liquid delivery means to said mixing chamber; an air passage disposed through said valve body and through said spray head for discharging air from said air delivery means to said mixing chamber; a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge air and liquid within the chamber to the atmosphere; an air valve mounted on said valve body and associated with said air passage, said air valve being selectively open and closed to respectively permit and prevent air flow through said air passage; a liquid valve mounted on said valve body and associated with said liquid passage, said liquid valve being selectively open and closed to respectively permit and prevent liquid flow through said liquid passage; valve activating means mounted on said valve body to open and close said air and liquid valves in such a manner that said liquid valve may be opened only if said air valve is first opened and said air valve is closed only if said liquid valve is first closed; an adjustable liquid flow regulator mounted on said valve body and associated with said liquid passage to adjustably meter liquid flow therethrough; a stop member disposed on said valve body to engage said liquid flow regulator and limit the maximum liquid flow through said liquid passage; and calibration means associated with said valve body adjacent said liquid flow regulator to indicate the position of said regulator and the liquid flow through said liquid passage.
 6. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising: a valve body; liquid delivery means interconnecting said valve body and said liquid source; air delivery means interconnecting said valve body and said air source; a spray head connected to said valve body and having an air-liquid mixing chamber therein; a liquid passage disposed through said valve body and through said spray head for delivering liquid from said liquid delivery means to said mixing chamber; an air passage disposed through said valve body and through said spray head for discharging air from said air delivery means to said mixing chamber; a discharge orifice disposed through said spray head communicating said mixing chamber with the atmosphere to discharge air and liquid within said camber to the atmosphere; an air valve mounted on said valve body and having an air spool piece disposed within said air passage and yieldably biased to a closed position in order to block air flow through said air passage, and partially depressible in order to permit unrestricted air flow through said air passage, said spool piece including air flow restriction means to limit air flow through said air passage when said spool piece is fully depressed; a liquid valve mounted on said valve body and associated with said liquid passage, said liquid valve being selectively open and closed to respectively permit and prevent liquid flow through said liquid passage; and valve activating means mounted on said valve body to open and close said air and liquid valves in such a manner that said liquid valve may be opened only if said air valve is first opened and said air valve is closed only if said liquid valve is first closed.
 7. Spraying apparatus for use with a liquid source and a pressurized air source to produce a fine liquid spray, said apparatus comprising: a valve body; a liquid delivery means interconnecting said valve body and said liquid source; air delivery means interconnecting said valve body and said air source; a spray head connected to said valve body and having an air-liquid mixing chamber therein; a liquid passage disposed through said valve body and through said spray head for delivering liquid from said liquid delivery means to said mixing chamber; a first air passage disposed through said valve body and through said spray head for discharging air from said air delivery means to said mixing chamber; a discharge orifice disposed through said spray head communicating said mixing chaMber with the atmosphere to discharge air and liquid within said chamber to the atmosphere; a first air valve mounted on said valve body and associated with said first air passage, said air valve being selectively open and closed to respectively permit and prevent air flow through said first air passage; a liquid valve mounted on said valve body and associated with said liquid passage, said liquid valve being selectively open and closed to respectively permit and prevent liquid flow through said liquid passage; an air blast orifice associated with said spray head; a second air passage disposed through said spray head and through said valve body and communicating with said air blast orifice to discharge air therefrom supplied by said air delivery means; a second air valve mounted on said valve body and associated with said second air passage, said second air valve being selectively open and closed to respectively permit and prevent air flow through said second air passage; and valve activating means mounted on said valve body to open and close said air valves and said liquid valve in such a manner that said liquid valve may be opened only if said air valve is first opened, said first air valve is closed only if said liquid valve if first closed, said second air valve may be opened only if said liquid valve is closed, and said second air valve is automatically closed when said liquid valve is opened.
 8. The spraying apparatus as in claim 7 including at least one pressure relief hole extending from said second air passage to the atmosphere to prevent air pressure in said second air passage from exceeding a predetermined level. 